2, 2-dialkyl alkanoic acid diesters of 2, 2-dialkyl glycols



United States Patent The present application is a continuation-impart ofapplication Serial No. 747,587, filed July 10, 1958, and now abandoned.

This invention relates to ester-type materials which are suitable foruse as synthetic lubricants. More particularly, the invention relates toester-type materials which are derived from acids in which the carbonatom alpha or beta to the carboxyl group i completely substituted withacyclic alkyl groups. Preferably, the substituted carbon atom is thealpha carbon atom.

Military use of turbojet and turboprop aircraft engines has led to aneed for specialized engine lubricants. These lubricants must permitstarting at very low temperatures encountered in arctic bases. They alsomust have adequate lubricity and stability at very elevatedtemperatures. IModern engines have exceedingly high power for their sizeand puta severe heat stress onthe lubricant.

The mineral lubricating oils which possess satisfactory low temperatureviscosities have generally been found to have flash points that aredangerously low and high temterature viscosities that .are below thoserequired. In other .words, when the mineral oil is thin enough at lowtemperatures, it is too thin and too volatile at higher temperatures. Inaddition, conventionally refined mineral oils deteriorate too rapidly athigh operating temperatures, even when compounded with the bestavailable antioxidants.

Recently, in an effort to obtain the superior lubricants needed forthese turbine-type engines, synthetic lubricants have been developed.Esters represent a class of materials which have attracted unusualinterest as synthetic lubricants. iDiesters are a preferred class ofesters. These materials are generally characterized by high viscosityindexes and flash points and lower pour points than mineral oils of acorresponding viscosity.

While the diesters offer many outstanding properties which enable themto be used as lubricants for turbojet and turboprop engine-s, thereremain characteristics in which they may be improved. To suchcharacteristics are thermal stability and hydrolytic stability.

In the more recent turbines, the normal bearing temperatures duringoperation reach as high as 475 F. With bearings next to the turbinewheel, a soak-back effect occurs following shutdown. Heat accumulated inthe turbine wheel disk flows into the cooler turbine bearings when theoil flow is stopped at time of shutdown. This may add another 100 to 160F. for a brief period following shutdown. The resulting temperatures arehigher than can be withstood by conventional diesters, regardless ofcompounding with additives. Lack of thermal stability. in thesematerials results in (a) engine deposits and (b) physical loss oflubricant due to partial volatilization of decomposition products.

Since all oil systems in aircraft collect small amounts of water fromtime to time, a diester lubricant should have hydrolytic stability. Lackof hydrolytic stability results in formation of volatile alcohols andcorrosive acids. Currently available diesters are not adequately stable.

Broadly stated, the present invention relates to estertype materialswhich are derived from organic carboxylic acids in which the carbon atomalpha or beta to the 3,256,321 Patented June 14, 1966 "ice carboxylgroup is completely substituted with acyclic alkyl groups. In oneembodiment the invention relates to diesters which are derived fromdicarboxylic acids in which the carbon atoms alpha to each of thecarboxyl groups is completely substituted with acyclic alkyl groups, andfrom either conventional monohydroxy alcohols or from monohydroxyalcohols in which the beta carbon atom thereof is completely substitutedwith alkyl groups or fluorine atoms. In a further embodiment theinvention relates to diesters which are derived from dicarboxylic acidsin which the carbon atoms beta to each of the carboxyl groups iscompletely substituted with acyclic alkyl groups and from monohydroxyalcohols in which the beta carbon atom thereof is completely substitutedwith either acyclic alkyl groups or fluorine atoms. In anotherembodiment the invention relates to esters prepared from monobasic acidsin which the carbon atom adjacent to the carboxyl group is completelysubstituted with acyclic alkyl groups and polyhydroxy alcohols in whichthe beta carbon thereof is completely substituted with acyclic alkylgroups. In still another embodiment the invention relates to the noveldicarboxylic acids in which the carbon atoms alpha-or beta to each ofthe carboxyl groups is completely substituted with acyclic alkyl groups.In yet another embodiment the invention relates to a process forpreparing the afore-mentioned .dicarboxylic acids. In yet still anotherembodiment the invention relates 'to complex esters which are preparedfrom (a) the afore-mentioned dicarboxylic acids, b) the aforementionedmonobasic acids, (c) the afore-mentioned polyhydroxy alcohols, and (d)the afore-mentioned monohydroxy alcohols.

Before proceeding to a description of the suitable starting materialsfor these ester-type materials, it may be well to set forth anexplanation of the theory associated with the function of thesematerials. While we do not wish to be bound by this explanation, webelieve the theory is as follows:

Thermal degradation of esters formed from aliphatic alcohols andaliphatic acids is initiated at the carbonyl oxygen and results in theformation of olefin and acid. This degradation arises from electronmigration after formation of an unstable ring structure. To form thisintermediate ring there must be hydrogen atoms in the alcohoI portion ofthe ester which are in the sixth atom positior from the carbonyl oxygen.These hydrogen atoms mus also be coplanar to the carbonyl group or musthave rota tional freedom if ring formation is to occur. The actior isindicated by the following diagram:

(6) 11 orr e Original state 0 (1) showing numbering II system a-ant O\HC \C-R Intermediate 0 ring formation Heat O HO H II Products after H CRelectron H-C H l migration Esters in which the six positions of thealcohol portion are completely substituted with alkyl groups preventthermal elimination through this mechanism because the formation of theabove foregoing ring structure is not possible and no hydrogen-s areavailable in the six position for transfer.

Alkyl groups on the alpha carbon of the acid portion of an estermolecule sterically hinder and reduce the availability of the carbonyloxygen for attack by oxygen, hydrogen, acids, or bases. In other words,the presence of such alkyl groups improves the hydrolytic stability ofthe ester molecule. The greater the size of the alkyl substituent, thegreater would be the hindrance and, accordingly, resistance tohydrolysis. Methyl groups in the alpha position to the carbonyl oxygenmeet the minimumrequirements.

Alcohols with alkyl groups or fluorine atoms on the carbon atom beta tothe hydroxyl group, and acids in which the carbon atoms either alpha orbeta to the carboxyl groups are completely substituted with alkylgroups, are referredto as hindered alcohols and acids. Esters preparedfrom alcohols and acids, both of which are hindered, possess boththermal and hydrolytic stability. If only the alcohol is hindered, theester possesses only thermal stability. If only. the acid is hindered,the ester possesses only hydrolytic stability.

We have found that substitution only on the beta carbon atoms of thedicarboxylic acid does not produce a noticeable or measurable effect onhydrolytic stability. Still further, we have found that esters preparedfrom hindered alcohols and dicarboxylic acids in which the carbon atoms,either alpha or beta to the carboxyl groups, are completely substitutedwith alkyl groups exhibit ther mal stability greater than is shown whenonly the alcohol is hindered. This discovery is surprising.

Before giving specific examples of the products and processes of thepresent invention it may be well at this time to describe the nature ofthe materials used and the processes involved.

In order to set forth clearly the nature of the present invention theterm ester as used herein and in the claims refers to the productderived by reacting an organic carooxylic acid with an organic hydroxycompound.

The hindered dibasic acids of the present invention have ilutaric acids:

2,2,4,4-tetraethyl 2,4-dimethyl-2,4-diethyl 2,4-dimethyl-2,4-dipropyl2,4-diethyl-2,4-dipropyl 2,4-diethyl-2,4-dibutyl 2,2,4,4-tetramethyl v2,2,4,4-tetrapropy1 2,2,4,4-tetrabutyl 4 Adipic acids:

2,2,5,5-tetraethyl 2,5-dimethyl-2,5-diethyl 2,5-dimethyl-2,S-dipropyl2,5-diethyl-2,5-dipropyl 2,5-diethyl-2,5-dibutyl 2,2,5,5-tetramethyl2,2,5,5 -tetrapropyl 2,2,5,5-tetrabutyl Pimelic acids:

2,2,6,6-tetraethyl 2,6-dimethyl-2,6-dipropyl 2,6-dimethyl-2,6-di'ethyl2,6-diethyl-2,6-dipropyl 2,6-diethyl-2,6-dibutyl 2,2,6,6-tetramethyl2,2,6,6-tetrapropyl 2,2,6,6-tetrabutyl Suberic acids:

' 2,2,7,7-tetraethyl 2,7-dimethyl-2,7-diethyl 2,7-dimethyl-2,7-dipropyl2,7-diethyl-2,7-dipropyl 2,7-diethyl-2,7-dibutyl 2,2,7,7-tetrarnethyl2,2,7,7-tetrapropyl 2,2,7,7-tetrabutyl Azelaic acids:

2,2,8,8-tetraethyl 2,8-dimethyl-2,8-diethyl 2,8-dimethyl-2,S-dipropyl2,8-diethyl-2,8-dipropyl 2,8-diethyl-2,8-dibutyl 2,2,8,8-tetramethyl2,2,8,8-tetrapropyl 2,2,8,8-tetrabutyl 2,2,8,8-tetraisopropyl2,2,8,8-tetratertiarybutyl Sebacic acids:

2,2,9,9-'tetraethyl 2,9-dimethyl-2,9-diethyl 2,9-dimethyl-2,9-dipropyl2,9-diethyl-2,9-dipropyl 2,9-diethyl-2,9-dibutyl 2,2,9,9-tetrarnethyl2,2,9,9-tetrapropyl 2,2,9,9-tetrabutyl Examples of suitable dibasicacids in which the carbon atom beta to the carboxyl group is completelysubstituted with acyclic alkyl groups are the following:

Beta acids:

3,3-dimethyl glutaric acid 3,3,5,5-tetramethyl pimelic acid3,3,6,6-tetramethyl suberic acid 3,3,6,6-tetraethyl suberic acid3,6-dimethyl-3,6-diethyl suberic acid 3,3,7,7-tetramethyl azelaic acid3,3,8,8-tetramethy1 sebacic acid Diesters prepared from hinderedalpha-substituted dibasic acids and conventional alcohols have thefollowing formula:

wherein R is an acyclic'alkyl group containing from 1 to 4 carbon atoms,R is an acyclic alkyl group containing from 1 to carbon atoms and n isan integer varying from 1 to 10. Example of suitable conventionalalcohols are the following:

n-Butanol n-Hexanol n-Octanol n-Decanol Z-ethylhexanol Isooctanoln-Dodecanol n-Tridecanol n-Hexadecanol n-Octadecanol 2-ethyl butanolIsodecanol Of the suitable alcohols listed above, the ones indicatedwith an asterisk are preferred.

Diesters prepared from hindered dibasic acids and hindered alcohols havethe following formula:

where A is selected from wherein R is an acyclic alkyl group containingfrom 1 to 4 carbon atoms, R, is an acyclic alkyl group containing from 2to 10 carbon atoms, X is either fluorine or an acyclic fiuoroalkyl groupcontaining from 1 to 10 carbon atoms, where B is selected from:'

wherein R is an acyclic alkyl group containing from 1 to 4 carbon atoms,n is an integer varying from 1 to 10, and n' is an integer varying from1 to 9.

The hindered alcohols of the present invention have one of the followingformulas:

R H F I l I R1C OH or XCOOH I ll RH FH where R is an acyclic alkyl groupcontaining from 1 to 4 carbon atoms, R is an acyclic alkyl groupcontaining from 2 to 10 carbon atoms, and X is either fluorine or anacyclic fiuoroalkyl group containing from 1 to 10 carbon atoms.

Examples of suitable hindered alcohols are the following:

2,2-dimethyl-1-pentanol 2,2-diethyl-1-butanol 2,2-dimethyl-l-hexanol2,2-dimethyl-l-butanol 2-methyl-2-ethyl-l-octanol2,2,4-trimethyl-l-pentanol 2,2-dirnethyl-1-octanol2,2-dirnethyl-l-decanol Z-methyl-Z-propyl-l-pentanol2-ethyl-2-propyl-l-hexanol 2-1nethyl-2-terti-ary amyl-l-butanol2-methyl-2-isopropyl-l-hexanol PREPARATION OF 2,2-DIMETHYL-1-HEXANOL 1.Intermediate: 4

(1) Sodium triethylmeth-oxide (2 Dimethylacetyl chloride (CH CHC(OOH+SOCl (CH CHCOCl where C(O) is C=O (3 Triethylcarbinyl isobutyrate (CH CONa+ (CH CHCOCl 2. 2,2dimethyl-1-hexanol:

The hindered monobasic acids of our invention have the formula:

wherein R R and R are acyclic alkyl groups containing from 1 to 18carbon atoms. Examples of suitable hindered monobasic acids are thefollowing:

2,2-dimethyl-1-butanoic acid 2,2-dimethyl-l-pentanoic acid2,2-dimethyl-l-hexanoic acid 2,2-dimethyl-l-heptanoic acid2,2-dimethyl-1-octanoic acid 2,2-dimethyl-l-nonanoic acid2,2-dimethyl-l-decanoic acid 2,2-dimethyl-l-hendecanoic acid2,2-dirnethyl-l-dodecanoic acid 2,2-dimethyl-l-tetradecanoic acid2,2-dimethyl-l-hexadecanoic acid 2,2-dimethyl-l-octadecanoic acid2,2-dimethyl-l-eicosanoic acid 2-methyl-2-ethyl-l-C -C -monocarboxylicacid 2-methyl-2-propyl-1-C -C -monocarboxylic acid 2-methyl-2-amyl-l-c-C -monocarboxylic acid 2,2-diethyl-1-C -C -monocarboxylic acid2-ethyl-2-propyl-l-c -C -monocarboxylic acid 2-ethyl-2-butyl-l-c -C-monocarboxylic acid 2-ethyl-2-amyl-l-C -C -monocarboxylic acid2,2-dipropyl-1-C -C -monocarboxylic acid 2-propyl-2-butyl-1-C C-monocarboxylic acid 2-propyl-2-amyl-l-C -c -monocarboxylic acid2,2-dibutyl-l-C -C -monocarboxylic acid 2,2-diamyl-l-c -c-monocarboxylic acid 2-buty1-2-amyl-1-C -C monocarboxylic acid2-hexyl-2-methyl-decanoic acid Of the above suitable hindered monobasicacids the ones indicated with an asterisk are preferred.

The hindered polyhydroxy alcohols of our invention have the followingformula:

wherein A has a formula selected from the group consisting of:

wherein R, R and R are acyclic alkyl groups containing from 1 to 4carbon atoms and n is an integer varying from 1 to 10.

Examples of suitable hindered polyhydroxy alcohol are the following:

Glycols:

1,3-propanediols 2,2-dimethyl 2,2-diethyl 2,2-dipropyl 2,2-dibutyl2-methyl-2-ethyl 2-n1ethyl-2-propyl 2-methyl-2-butyl 2-ethyl-2-propyl2-ethyl-2-butyl 1,6-hexanediols 2,2,5,5-tetramethyl2,6-dimethyl-2,6-diethyl 2,6-dimethyl-2,6-dipropyl2,6-dimethyl-2,6-dibutyl 2,6-diethyl-2,6-dipropyl 2,2,5,5-tetraethyl2,2,5,5-tetrabutyl 2,5,5-trimethyl-2-propyl-3-ethyl2,2,5,5-tetramethyl-3,4-diethyl 1,7-heptanediols2,4,6-trimethyl-2,6-dipropyl 2,2,4,6,6-pentamethyl-3-ethyl1,8-octanediols 2,7,7-trimethyl-2-propyl 2,2,4,5,7,7-hexamethyl2,2,7,7-tetramethyl-3-ethyl 2,2,4,7,7-pentamethyl 1,10-decanediols2,2,9,9-tetramethyl 8 wherein R R and R are acyclic alkyl groupscontaining from 1 to 18 carbon atoms and where A is selected from thegroup consisting of:

(A) AB-A1-BA where A equals hindered monohydroxy alcohol, B equalshindered dibasic acid, and A equals hindered polyhydroxy alcohol; and

where B equals hindered dibasic acid, A equals hindered polyhydroxyalcohol, and D equals hindered monobasic acid.

The hindered dibasic acids per se which form an embodiment of ourinvention have been described previously.

Our invention relates also to the process for preparing the hinderedalpha-substituted dibasic acids. This process can be described ascomprising the following steps. (a) Preparation of 2,2-dialkylacetylhalide,

(b) Preparation of alkali metal salt of trialkylcarbinol,

(c) Reaction of -2,2-dialkylacetyl halide with the alkali metal salt oftrialkylcarbinol to form trialkylcarbinyl- 2,2-dialkylacetate inpresence of liquid ammonia,

(d) Preparation of sodio salt of trialkylcarbinyl-2,2-dialkylacetate byreaction with metallic sodium in liquid ammonia, I

(e) Reaction of sodio salt of trialkylcarbinyl-2,2-dialkylacetate withan alkylene dihalide,

(f) Hydrolysis of product of step (e) to produce the 2,2,-8,8-tetraalkylsubstituted acid.

' In a specific embodiment, the preparation of tetraethylazelaic acidcomprises the following steps:

(a) Synthesis of the intermediates:

(1) Preparation of diethylacetyl chloride:

(C H CHC(O) 0H+SOCl (C H CHC(O)Cl (2) Preparation of sodiumtriethylmethoxide:

(3) Preparation of triethylcarbinyl Z-ethylbutyrate:

(C H CH0 (0) 00 2115)::

(b) Synthesis of di(triethylcarbinyl) 2,2,8,-8atetraethylazelate:

, Liq. NH3

I (CzH5)2C U (0)0 C (0:;H BrC HzC HzGHgO HzCHzBr (IJHZC mo (0211920 (0')00 21193 CH2 CHzC H20 (02 92 00 2 5) a Dioxane While the purpose of thisinvention is to provide materials which are especially useful in theformulation of lubricants for use in turbojet and turboprop engines, thenovel diesters herein described may find use in wide temperature rangegreases, high temperature heat transfer fluids, hydraulic fluids, andlubricants for precision instrument bearings. The novel diesters of thisinvention are materials which provide hydrolytic stability to an extenthitherto unknown.

Conventional diesters were used as standards for comparison with thehindered diesters of this invention. Diisooctyl azelate, di-Z-ethylhexylsebacate, and diisobutyl azelate are commercially available diesterswhich were used per se. Di-Z-ethylhexyl azelate is also commerciallyavailable, but the material used was purified by vacuum distilling, toobtain a center cut, and then filtering through alumina. Di-n-octylazelate was prepared from commercially available materials. Itspreparation is shown in the examples.

In order to disclose the nature of the present invention still moreclearly, the following illustrative examples will be given. It is to beunderstood that the invention is not to be limited to the specificconditions or details set forth in these examples except insofar as suchlimitations are specified in the appended claims.

Example I.Preparatin of dien-octyl azelate Materials Moles Grams Azelaicacid 1 1-octanol Toluenesulfonic acid B enzene VOON} grams of l-octanol,2.0 grams of toluenesulfonic acid,

and 150 cc. of benzene to the reaction flask. Heat was applied andstirring commenced. Reflux initially was a 95 C. and continued for 8hours, at which time the reflux temperature had risen to 1110* C. Duringthis period, 36 ml. of water was removed and collected in the watertrap. The reaction mixture was then transferred .to a separatory funneland washed with 2 X 250 ml. portions of 5 percent aqueous sodiumcarbonate solution. It was then washed with 5 x 250 ml. portions of tapwater until the pH (via Hydrion paper) was 7. The crude diester wasdried over anhydrous magnesium sulfate and then filtered through aone-inch cake of Hyflo filter aid. The filter aid was washed with 100ml. of benzene and the benzene wash added to the product layer. Thecrude mixture (653 grams) was charged to a simple vacuum distillationsetup. Using a water aspirator, benzene solvent was removed. Using avacuum pump, a forecut which included excess alcohol was removed at 0.65mm. Hg up to a vapor temperature of 187 C. At 0.07 mm. Hg 364.0 grams ofdiester (id-n-octyl azelate) was collected. A cut distilling between 202-2 35 C. at 0.17 mm. Hg weighed 18.2 grams. The bottoms weighed 7.5grams. The diester cut was percolated through 104 grams of alumina. Thefiltrate had an acid number of 1.2 and a saponification number of 269.

The acid number was further reduced to 0.0 2 by percolation throughbasic ion exchange resin.

Example Il.-Preparati0n of di-2,2-dimethylhexyl azelate Materials Molesl Grams 2,2-dimethyl-1-hexanol 1 1. 11 141. 8 Azelaic acid 0. 56 104. 5Benzene (solvent and water entrainer (250 cc.) P-toluenesulfonic acid(catalyst)- 2 0 Ether (wash solvent) (650 cc discussion.

A pparatus.-Two liter, three necked, round bottom flask; Truborestirrer, thermometer; Barrett water trap; water-cooled reflux condenser.

Pr0cedure.To the reaction flask were charged 141.8 grams of2,2-dimethyl-l-hexanol, 104.5 grams of azelaic acid, 250 cc. of benzene,and 2 grams of p-toluenesulfonic acid. This mixture was heated withstirring at reflux for 8 hours, during which time 20.5 cc. of water wascollected in the Barrett trap. In an additional 8 hours of heating atreflux with stirring, no additional water was collected. The reactionmixture was transferred to a separatory funnel and washed with 2 x 100cc. portions of sodium carbonate solution which emulsified; but

after standing overnight, it separated when 400 cc. of ether was added.This ethereal layer was then washed with 2 x 100 cc. portions of water,dried over calcium sulfate, and filtered through a three-inch cake gramsof alumina). The alumina was washed with 150 m. of ether. The etherealfiltrate and the ether wash of the alumina were combined and stripped ofbenzene and ether up to C. on a water aspirator. At 0.14 mm. Hg using avacuum fractionation setup, 16 3.4 grams of di- 2,2-dimethylhexylazelate was separated between 176- 191 C. vapor temperature. A forecut10 grams) and the still bottoms (14 grams) were also obtained. The yieldof the diester based on the alcohol charged is 72.5 percent. The acidnumber of the distilled diester was 0.7 6. The acid number was reducedto 0.04 by percolation through basic ion exchange resin.

Example III.Pre'parati0n 0f di-2,2-diethylbutyl azelate Materials MolesGrams 2,2-diethyl-1-butanol l 0.95 121.5 Azelaic acid 0. 475 89.4Benzene (250 cc.) p-Toluenesulfonic acid Ether. (650 cc.)

Example IV.Preparation 0 di-2,2-dimethylamyl azelatr Materials MolesGrams Azelaic acid Q 2,2-dimethyl-1-pentanol 12 p-Toluenesulfonic acidBenzene. (200 cc.

A ppamtus.Same as in Example II.

Pr0cedure.-Charged azelaic acid (94 grams), 2,2-di methylpentanol (128grams), toluenesulfonic acid (1 grams), and benzene (200 cc.) to thereaction flasl Heating and stirring were commenced, and at reflux (100-water was collected. The crude diester mixture was filtered through 185grams of alumina. The alumina was Washed with pentane and the pentanewash added to the diester filtrate. Pentane, benzene, and light endswere removed up to 166 C. pot temperature at .07 mm. Hg pressure. Thestripped diester, diluted 50 percent by volume with pentane, waspercolated through alumina and then a 12- inch column of the basic ionexchange resin (IR-45). Pentane was removed up to 100 C. at .1 mm. Hg.The acid number of this undistilled diester was 0.03. It weighed 170grams (88.5 percent yield).

The second batch was prepared using the same procedure except that thediester was distilled. The di(2,2- dimethylamyl) azelate distilledbetween 160180 C. at .1 mm. Hg pressure. The acid number of thedistilled diester after percolating through basic ion exchange resin(IR-45) was 0.01. Over-all yield based on acid charged was 76 Weightpercent. Data on only the distilled diester are shown in the tables.

Example V.Preparation of di-n-ctyl-2,2,8,8- tetraethylazelate A.Preparation of 2,2,8,8-tetraethylazelaoyl chloride.

Materials Moles Grams 2,2,8,8-tetraethylazelaic acid 1 282 84. 7 Thionylchloride 643 76. 7 Benzene (solvent) (450 cc.)

Prepared in accordance with synthesis steps outlined in previousdiscussion.

A pparatus.--Two-liter, three-necked flask; Trubore stirrer; refluxcondenser; thermometer.

Procedure.-Charged 76.7 grams of thionyl chloride to the dry reactionflask along with 84.7 grams of 2,2,8,8- tetraethylazelaic acid and 450cc. of benzene. Stirring was commenced and the mixture heated at 78 C.untilhydrogen chloride gas evolution ceased (eight hours). The crudemixture was stripped of excess thionyl chloride and benzene atatmospheric pressure up' to 122 C. pot

temperature. On house vacuum at maximum pot temperature of 118 C.,remaining traces of light ends were removed. The acyl halide bottomswhich solidified on cooling weighed 92 grams (theoretical 95 grams).This product analyzed 17.5 percent Cl (theoretical 21).

B. Preparation of di-(n-octyl)-2,2,8,8-tetraethylazelate:

Appa ratus.Two-liter, three-necked, round-bottomed flask; Truborestirrer; Dry Ice-cooled condenser; bubble counter; drying tube; droppingfunnel.

Pr0cedure.-Charged 1,000 cc. of ammonia to the dry nitrogen-flushedreaction flask; then 0.5 gram of sodium metal was added. After thesolution turned blue, the liquid was blown with dry air until the colorwas discharged; then 1.0 gram of ferric nitrate was added. Stirring wascommenced, and the remaining 22.2 grams of sodium metal was added insmall portions over a period of 2.0 hours. The temperature of thereaction flask was held at -35 C. Ten minutes after the addition of thesodium was completed, the blue color was discharged. To this mixture wasadded dropwise 128.5 grams of l-octanol diluted with 300 cc. of dryether. After the final addition of l-octanol, an additional 200 cc. ofdry ether was added. Ammonia was allowed to evaporate overnight; thennitrogen was blown through the pot mixture, which was heated on a steambath for five hours. During this period, 500 cc. of ether was added.Next, 166.2 grams of 2,2,8,8-tetraethylazelaoyl chloride in 300 cc. ofdry ether was added at such a rate as to maintain constant reflux andcontrol the reaction. Poststirring was continued for three hours. Icewater (500 cc.) was added cautiously over 30 minutes. The mixture wasfiltered to remove a small quantity of flocculent which hamperedseparation of the water and ether layers. The two layers were thenseparated, and the ether wash of the aqueous layer was combined with theether layer. The ether layer was washed with 2 X 200 cc. portions of 10percent sodium hydroxide and finally with water until the wash water wasneutral to pHydrion" paper. The ether layer was filtered through aone-inch cake of Hyflo filter aid and dried over calcium sulfate. Etherwas removed by heating to 60 C. at atmospheric pressure after filteringthrough grams of alumina. The crude diester was charged to a vacuumdistillation setup and stripped up to 200 C. at 0.1 mm. Hg pressure. Themaximumvapor temperature during this period was 68 C. Overhead weighed16.7 grams. The botoms product weighed 232.5 grams. The product diesterwas diluted 5 0 percent by volume with pentane and percolated through180 grams of alumina followed by a 12-inch column of basic ion exchangeresin (IR-45). Both columns were flushed with pentane and the wash addedto the efiinentdiester. Pentane was removed up to C. at 0.1 mm. Hgpressure. The product diester Weighed 177.5 grams. This product had anacid number of 0.02 and analyzed 75.0 percent carbon (theoretical 75.7)and 12.2 percent hydrogen (theoretical 12.2).

Example VI.Preparali0n of di-2,2-dimethylamyl-2,2,8,8,-tetraethylazelate 1 Prepared in accordance with synthesis stepsoutlined in previous discussion.

Apparatus.Two-liter, three-necked flask; Trubore stirrer; refluxcondenser; thermometer.

Pr0cedure.Charged grams of thionyl chloride to the dry reaction flaskalong with 154 grams of 2,2,8,8- tetraethylazelaic acid in 500 cc. ofbenzene. Stirring was commenced, and the mixture'was heated at 78 C.until hydrogen chloride gas evolution ceased (12 hours). The crudemixture was stripped of excess thionyl chloride and benzene atatmospheric pressure up to 125 C. pot temperature. temperature of 118C., remaining traces of light ends were removed. The acyl halide bottomsweighed grams (theoretical 174 grams).

B. Preparation of di(2,2-dimethylamyl)-2,2,8,8-tetraethylazelate:

Materials Moles Grams Ferric nitrate (catalyst for amide prepara,

tion 1. 0 Ammonia (solvent and reactant) (1, 000 cc.)2,2-dimethyl-1-pentanol 1 116 Sodium 1 23 Ether (solvent) (1, 500 cc.)2,2,8,8-tetraethylazelaoyl chloride 0. 504 170 On house vacuum atmaximum pot ring was commenced, and the remaining 22.5 grams of sodiumwas added in small portions over a period of one hour. The temperatureof the reaction flask was held at -35 C. Ten minutes after the additionof sodium was completed, the blue color was discharged. To this mixturewas added dropwise 116 grams of 2,2-dimethylpentanol diluted with 300cc. of dry ether. After the final addition of 2,2-dimethylpentanol,ammonia was allowed to evaporate overnight. Nitrogen was blown throughthe reaction mixture, which was heated on a steam bath for six hours.Two hundred cc. of ether was added followed by 170 grams of2,2,8,8-tetraethylazelaoyl chloride in 300 cc. of dry ether at such arate as to maintain constant reflux and control the reaction.Poststirring was continued for three hours at full reflux. Ice water(750 cc.) was added cautiously over /2 hour. The mixture was filtered toremove flocculent material and transferred to a separatory funnel inwhich two layers formed. The water layer was removed and washed with 200cc. of ether and the ether wash combined with the ether layer. The etherlayer was washed with water until the resulting water wash was neutralto pHydrion paper. The ether layer was dried overnight over calciumsulfate, filtered through alumina, and stripped of ether up to 60 C. atatmospheric pressure. The crude diesterv was charged to a vacuumdistillation setup and stripped up to 192 C. at 0.25 mm. Hg pressure.The maximum vapor temperature was 23 C. The product diester (bottoms)was di.

luted 50 percent by volume with pentane and percolated through a 12-inchcolumn of basic ion exchange resin (IR-45 The column was washed withpentane and the washings combined with the product-containing layer.Pentane was removed up to 115 C. at 0.3 mm. Hg pres- IABLE I.ANALYTICALDATA ON HINDERED ALCOHOLS AND ACID OF EXAMPLES I-VI 14 sure. The productweighed 198.5 grams. The acid number of the diester was 0.64.

TESTING PROCEDURES (EXAMPLES I-VI) Thermal stability testing.The thermalstability of each of the esters prepared was determined using a simpletest. A 25-ml. sample of the ester to be tested was charged to a tubecm. long 25 cm. in diameter, fitted with a side arm 8 cm. from the topof the tube to which was attached through a standard taper joint 21U-tube containing mercury. The top of the test tube was fitted with a24/40 standard taper joint in' which Was fitted a stopcock with an 8-mm.I.D. tube extending inside the test tube to within 10 cm. of the bottom.The stopcock was opened, nitrogen gas was introduced, and the testingtube flushed with the U-tube removed.- The U- tube was then inserted,flushed with nitrogen, and a slight positive nitrogen pressure allowedto remain. The tube was immersed in an aluminum block bath and heated to550 C. for 48 hours. The acid numbers were then determined by means of aPrecision Automatic Titrator, using ASTM procedure D-664-54.

In calculating the percent decomposition, as shown in Table III, thesaponification number was assumed to be equivalent to 100 per-centdecomposition.

H ydrolytic stability testing-Timed saponification numbers were made onboth the reference diesters and the hindered diesters. The timeintervals chosen were 0.5

hour, 2 hours, 4 hours, and 24 hours. The saponification numbers weredetermined using ASTM procedure D939-54.

Physical tests. The various physical tests conducted used standard ASTMprocedures.

Melting Boiling Point, 0. Boiling Point, 0. Acid No.

C. (Literature) Tetraethylazelaic acid 135136 378-380 (calculated 380).2,2-dimethy1-1-hexanol -75 at 14 mm. Hg -82 at 14 mm. Hg2,2-diethyl-1-butanol -93 at 25 mm. Hg 92 at 25 mm. Hg

1 JAGS, 55, 1121 (1933). 2 JACS, 78, 5416 (1956). r 3 Gauge notcalibrated.

TABLE II.-PHYSICAL PROPERTIES OF DIES'IERS SHOWN IN EXAMPLES I-VIViscosities Example Vis- ASTM Density Refractive Number Diester cositySlope at Index at Cs. at Cs. at Cs. at Index 25 C. 25 0., NaD -40 F. F.210 F Conventional:

Diisooctyl azelate 1, 285 12.54 3. 38 164 0.686 0. 9131 1. 443:Di-2ethylhexy1sebacate 1, 400 12.80 3.34 154 0.706 0.9106 1. 449Diisobutyl azelate 254 5. 58 1. 90 0.802 0. 9281 1. 4341 I Di-n-octylazelate Solid 11. 32 3. 25 175 0. 674 0.9091 1. 447 Di-2-ethylhexylazelate 1, 242 10. 96 2. 99 145 0. 676 0. 9135 1. 448 Hindered:

Di-2,2-dimethylhexy1 azelate 4, 722 15. 90 3. 65 133 0. 725 0. 90931.447 Di-2,2-diethylbutyl azelate 8, 343 21. 03 4. 48 1, 414 0. 700 0.9323 1. 455 D ifif-dimethylamyl azelate (redis- 3, 13. 26 3. 23 126 0.736 0.9151 1. 445

1 e Di-n-octy1-2,2,8,8-tetraethy1 azelate Not run 43. 27 6. 33 104 0.736 0. 9082 1. 456 Di-2,2-dimethylamyl-2,2,8,8-tetraethyl- Not run118.60 8.62 0.832 0.9113 1.454

azelate.

TABLE III.-THERMAL STABILITY STUDIES (EXAMPLES I-VI) m1. sample heatedin nitrogen atmosphere for 48 hours at 550 F.]

Acid No. Percent 2 De- (After) composition Saponification ExampleDiester Acid No. Number, mg.

Number (Before) KOH/gm.

Run Run Run Run No. 1 No. 2 No. 1 No. 2

Conventional:

Diisooctyl azelate 0. 02 72 95 26. 5 34. 9 272 Di-2-ethylhexyl sebacate.0. 04 43 53 16. 2 19. 9 266 Di-isobutyl azelate 0. 01 57 61 15. 5 l6. 6368 Di-n-octyl azelate 0. 03 49 67 17. 8 24. 4 275 D1-2 ethylhexylazelate 0. 07 47 17.3 14. 8 271 Hindered:

Di-2,2-dimethylhexyl azelate- 0. 04 4. 4 4. 9 1. 6 1. 8 273Di-2,2-diethylbutyl azelate. 0. 02 7. 1 5. 9 2. 6 2. 1 275Di-2,2-dimethylamyl azelate. 0.01 13 13 4. 4 4. 4 296D1-n-1oti;tyl-2,2,8,8tetraethyl 0. 03 56 20. 2 214 (Theor.)

aze a e. Di-2,2-dimethylamyl-2,2,8,8,- 0. 64 8 3. 5 226 (Thcor.)

tetraethyl azelate.

1 Acid number in mg. KOH/g'm. 2 100% decomposition is equal tosaponification number.

TABLE IV.HYDROLYTIC STABILITY STUDIES (EXAMPLES I-VI) Saponificationnumber Example Diester Acid mg. KOH/gm. 2 24 Number Number Hours HoursHours Theo- Actual (30 retlcal Minutes) Conventional:

Diisooctyl azelate 0.02 272 Di-Z-ethylhexyl sebacate 0. 04 262Di-isobutyl azelate 0.01 334 Di- -octyl azelate. 0. 03 272 D1 2ethylhexyl azelate 0. 07 272 Di-2,2-dimethylhexyl azelate n 0.04 272Di-2,2-diethylbutyl azelate 0. 02 272 Di-2,2-dimethylamyl azelate 0.01292 Di-n-octyl-2,2,8,8, tetraethyl azelate 0. 03 214 18 25 22 33Di-2,2-dimethylamyl-2,2,8,8

tetraethyl azelate 0. 64 226 19 19 21 76 Example VIl.Preparati0n of 2,2,8,8-tetraethylazelaic acid A. Preparation of 2-ethylbutyryl chloride:

Materials Mole Moles Quantity, g.

-Weight 2-ethylbutyric acid 116. 16 15 1, 743 Thionyl chloride, Eastmangrade... 118. 98 16. 8 2, 000

Pr0cedure.To 2000 grams of thionyl chloride maintained at C.,2-ethy1butyric acid (1743 grams) was added dropwise. The mixture wasthen heated to 75 C. for four hours to drive out the remaining sulfurdioxide. The product (1685 grams, 83.5 percent) distilled at 135- 137 C.through a six-inch vacuum jacketed column packed with glass helices.

B. Preparation of triethylcarbinyl 2-elthylbuty-rate:

Materials Mole Moles Quantity Weight Ferric nitrate 1 g. Ammonia,anhydrous 2,000 cc. Sodmm, purified lump 22. 997 6.1 140 g.Tnethylcarbinol, Eastm 116 6 696 g. 2-ethylbutyryl chloride 134. 61 6807 g. Ether, anhydrous rea ent 1,500 cc.

A solution of 807 grams of Z-ethylbutyryl chloride in 200 cc. of etherwas added dropwise to the reaction mixture. This was then stirred forone hour and heated under reflux for another hour. Water was added todissolve the solids. The ethereal solution was washed with .10 percentsodium hydroxide, washed with water until neutral, and dried overcalcium sulfate. Fractional distillation of the crude mixture yielded1067 grams (83.5 percent) of triethylcarbinyl 2-ethylbutyrate (BR 102-105 C. at 10 mm.).

C. Preparation of di-(triethylcarbinyl)2,2,8,8 tetraethylazelate:

Procedure.Sodium amide was prepared from grams of sodium and 2 liters ofliquid ammonia. Triethylcarbinyl 2-ethylbutyrate (1067 grams) was addeddropwise, and-the mixture was stirredfor 1.5 hours. A solution of 575grams of dibromopentane in 200 cc. of ether was added dropwise, andstirring was continued for 1.5 hours. More ether (400 cc.) was added,and the ammonia was allowed to evaporate. After refluxing the solutionone hour, Water was added to dissolve the solids present. The etherealsolution was washed with water until neutral, dried over calciumsulfate, and reduced to small volume under vacuum. Thecrude residueweighing 1002 grams was hydrolyzed without further purification. 1

- 17 t D. Hydrolysis of di-(triethylcarbinyl) 2,2,8,8-tetraethylazelate:

Procedure.Concentrated hydrochloric acid (450 cc.) was slowly added to arefluxing solution of the crude di-(triethylcarbinyl)2,2,8,8-tetraethylazelate in 500 cc. of dioxane. After refluxing for twohours, 945 cc. of azeotropic distillate had been collected. Water wasadded to precipitate the crude acid, which was collected on a filter,recrystallized twice from 90: 10 ethanol-methanol and Water and oncefrom acetone-naphtha. The purified acid (M.P. 142-l43.5 C.) obtainedweighed 461.5 grams (61.5 percent, based on triethylcarbinyl2-ethylbutyrate). Acid number: calculated for tetraethylazelaic acid,374; found, 381.

Example VIII.Breparatiori of Z-methyl-Z-ethyl-lpentanol A. Preparationof Z-methylpentanoyl chloride:

Materials Mole Moles Grams Weight 2-methylpentanoic acid 116. 16 10. 71, 242 Thionyl chloride 118. 98 12. 2 1, 457.

B. Preparation of triethylcarbinyl Z-methylpentanoate Mole WeightMaterials Quantity Moles Ferric ni ate Ammonia- Triethylcarbi2-methylpentanoyl chloride g Pr0cedure.To 2000 cc. of liquid ammonia ina dry nitrogen flushed flask was added 0.5 gram of sodium metal. Theblue color was discharged with a stream of dry air; then 1 gram offerric nitrate was added. The remaining sodium (139.5 grams) was addedin small portions with stirring. To this mixture was added a solution of696 grams of triethylcarbinol in 500 cc. of dry ether. The ammonia wasallowed to evaporate overnight, and the reaction mixture was thentreated with a stream of nitrogen and heated under reflux for 15 hours,1500 cc. of ether being added to the reaction flask during this time.

Next, a solution of 825 grams of Z-methylpentanoyl chloride in 200 cc.of ether was added dropwise over a 4-hour period. Stirring was continuedfor 1 hour. Water (1500 cc.) was slowly added. The contents of the flaskwas filtered, and the product was extracted with ether. The ethersolution was washed with two 250-cc. portions of percent sodiumhydroxide and then with water until the wash water was neutral, driedover calcium sulfate, filtered, and freed of solvent at atmosphericpressure. The residue was vacuum fractionated. The

18 product, triethylcarbinyl 2-methylpentanoate (930 grams; 72.5percent) distilled at 9210l C. at 10 mm. Hg.

C. Preparation of triethylcarbinyl 2-methyl-2-ethylpentanoate:

Materials Mole Quantity Moles Weight Ferric nitrate 1 Ammnn ia Sodium22. 997

Triethylcarbinyl 2-methylpentanoate. 214

%tt iyl bromide 108. 98

Procedure-To 2000 cc. of liquid ammonia in a dry nitrogen-flushed flaskwas added 1.0 gram of sodium. The blue color was discharged with astream of dry air;

, then 1.0 gram of ferric nitrate was added. The remaining sodium (99grams) Was added in small portions with stirring. To this mixture,triethylcarbinyl 2-methylpentanoate (930 grams) was added dropwise.Stirring was continued for two hours after the addition was completed.Next, a solution of 474 grams of ethyl bromide in 300 cc. of ether wasadded dropwise. The ammonia was allowed toevaporate, and ether (1100cc.) was added to facilitate stirring. Suflicient water (about 1500 cc.)was added to dissolve the solids formed. The contents of the flask werefiltered, and the product was taken up into ether. The ether solutionwas washed with water until neutral, dried over calcium sulfate,filtered, and freed of solvent at atmospheric pressure. The residue wasfractionated. The overhead temperature was taken to 115 C. at 12 mm. Hg.The residue (705 grams) was reduced to the alcohol without furthertreatment; 1

D. Reduction of triethylcarbinyl 2-methyl-2-ethylpentanoate to2-methyl-2-ethylpentanol:

Pr0cedure.A mixture of 100 grams of lithium aluminum hydride and 1000cc. of dry ether in adry nitrogen-flushed flask was stirred and heatedunder reflux for 5 hours using a steam bath. Triethylcarbinyl 2-me-thyl-Z-ethylpentanoate (705 grams) was added dropwise to the reactionmixture. the mixture was refluxed for 16 hours. Water was added veryslowly until hydrogen evolution ceased; then 50 percent H SO was addeduntil the solution was acidic. Additional water had to be added tocomplete solution of the solids in the flask.

The product was taken up into ether, washed with two 300-cc. portions of10 percent sodium hydroxide and with water until neutral, dried overcalcium sulfate, filtered, and freed of solvent at atmospheric pressure.The residue was vacuum fractionated. Triethylcarbinol weighing 80.4grams distilled at.7682 C. at 48 mm. Hg 2- methyl-2-ethyl-l-pentanol(345 grams; 65 percent) distilled at 90' C. at 25 mm. Hg.

Example IX .-Prepa'rati0n of di (2-methyl-Z-etlzylpentyl)2,2,8,8-tetraetlzylazelate Preparation of 2,2,8,8-tretraethylazelaylchloride:

Following the final ester addition,

Procedure-A mixture of 156.5 grams of 2,2,8,8-tetraethylazelaic acid,156.5 grams of thionyl chloride, 200 cc. of benzene, and 2 drops ofpyridine was heated to 45 C. for one hour and then at reflux for twohours. The benzene and thionylchloride were distilled from the reactionmixture, finally heating to 150 and using moderate vacuum to remove theremaining volatile materials. The residue was used in the followingreaction without further treatment.

Acyla-tion of Z-methyI-Z-ethylpentanol with 2,2,23,8- tetraethylazelaylchloride:

Materials Mole Weight 7 Quantity Moles Ferric nitrate Ammonia2-1nethyl-2-ethylpentanel. 2,2,8,8-tetraethylazelayl chloride EtherSodium 2,500 cc 43.2 g

Procedure-To 1500 cc. of liquid ammonia in a dry nitrogen-flushed flaskwas added 0.5 gram of sodium metal. The blue color was discharged with astream of dry air; then 1 gram of ferric nitrate was added. Theremaining sodium (42.7 grams) was added in small portions withstirringover a two-hour period. To the sodium amide mixture a solutionof 245 grams of Z-methyl- Z-ethylpentanol in 400 cc. of dry ether wasadded slowly. The ammonia was allowed to evaporate overnight. Themixture was refluxed for eight hours while a .stream of, nitrogen waspassed through it, 500 cc. of dry ether being added to the reactionmixture during this time. Next, the tetraethylazelayl chloride preparedfrom 0.94 mole of acid was dissolved in 500 cc. of dry ether and addeddropwise to the reaction mixture at such a rate as to maintain constantreflux. This was then refluxed for one hour, and water (1500'cc.) wasadded. The contents of the flask were filtered, and the product wastaken up into ether, washed with two 250-c-c. portions of 10 percentsodium hydroxide and with water until neutral, dried over calciumsulfate, filtered through Hyflo, and freed of solvent at atmosphericpressure. Volatile materials were removed by heating the mixture to 195C. (vapor temperature: 88 C.) at 0.5 mm. Hg pressure. The product esterwas the residue (436.5 grams; 89 percent).

The residue was refluxed for two hours with 400 cc. of 0.5 N alcoholicpotassium hydroxide. The temperature of the reaction mixture was about78 C. Next, petane and water were added, and the organic layer waswashed with water until neutral, filtered through Hyflo, and reduced tosmall'volume using a water aspirator. The infrared spectrum of thesample showed that it was free of anhydride. Acid number of the productwas 0.32. In order to reduce the acid number, the ester was dilutedwith-pentane and percolated through a 12Finch column of basic AmberliteIR-45. The pentane was removed by heating to 120 C. under oil pumpvacuum. After filtering through a small inch-thick cake of Hyflo, theester was still slightly hazy. It was dried over calcium sulfate forseveral days and filtered again. The product weighed 340 grams and hadan acid number of 0.16. After another treatment with IR-45, the acidnumber was 0.04. Gas-liquid partition chromatography indicated that themajor component comprised 79.4 percent of the sample.

Example X .Preparation of di-(2,2-dimethyl/texyl)Z,2,8,8-tefraetllylazelate Procedure 'io 600 grams of refluxing2,2-dimethylhexanol-1 in a dry flask, sodium (35 grams) was added insmall portions over a period of 2.5 hours. The mixture was refluxed forone hour, and then a solution of 0.75 mole of crude tetraethylazelaylchloride in 300 cc. of dry ether was added dropwise. The temperature ofthe reaction mixture remained at 80 C. during the acid chloride additionwithout external heating. Refluxing was continued for two hours afterthe addition. Enough water was added to dissolve the solids formed. Theproduct was taken up in ether, washed twice with 250 cc. of aqueous 10percent sodium hydroxide and by water until neutral, dried over calciumsulfate, and reduced to small volume at atmospheric pressure. Remainingvolatile materials were then removed by heating to 200 C. at 0.5 mm. Hgpressure. Weight of the residue was 378 grams (96 percent).

The ester was refluxed for two hours with 0.5 N alcoholic potassiumhydroxide. The base was washed from the ester and the ester dried overcalcium ulfate. Acid number of the product was 0.23. This was percolatedthrough Amberlite IR45, which reduced the acid number to 0.01. Theinfrared spectrum indicated the absence of anhydride. Gas-liquidpartition chromatography furnished an assay of 91.5 percent.

Example XI.Preparati0n 0 di-(2,2-dimethyloctyl)2,2,8,8-tetmethylcrzelate This product was prepared by the sameprocedure as used in Example X.

Example XlL-Preparation of di-(2,2-dimethyldecyl)2,2,8,8-tetraethylazelate This product was prepared by the sameprocedure as used in Example X.

Example XIII.-Preparati0n of di-(2,2-dimethylhexyl)2,2,6,6-tetramethylpimelate 2,2,6,6-tetramethylpimelic acid was preparedby a procedure similar to that used in Example VII.

The ester was prepared by a procedure similar to that used in ExampleIX.

Example XI V.Preparat1'0n of 2,8-dimethyl-2,8- dipropylazelaic acidPr0cedure.Sodium amide was prepared from grams of sodium and 2 liters ofliquid ammonia using ferric nitrate as catalyst. Triethylcarbinyl2-methylpentanoate (1072 grams) was added dropwise, and the mixture wasstirred for two hours. A solution of 575 grams of 1,5-dibromopentane and500 cc. of ether was added dropwise, and stirring was continued for onehour following the addition. Allowing the ammonia to evaporate overnightresulted in loss of part of the reduction mixture through foaming. Themixture was heated for one hour to expel remaining ammonia, andsuflicient water was added to dissolve the solids in the flask. Theproduct was taken up into ether, washed with water until neutral, anddried over calcium sulfate. The solution was filtered and freed ofsolvents by distillation at atmospheric pressure. Distillation at 10 mm.pressure yielded 103 grams at 4095 C. and 106 grams of triethylcarbinylZ-methylpentanoate at 97-101 C. The crude product (residual) weighed882.5 grams and was hydrolyzed without further purification.

2i B. Hydrolysis of di-(triethylcarbinyl) 2,8-dimethyl-2,8-dipropylazelate:

Prcedm'e.To a refluxing solution of 882.5 grams crudedi-(triethylcarbinyl) 2,8-dimethyl-2,8-dipropylazelate in 500 cc. ofdioxane was slowly added concentrated hydrochloric acid (400 cc.). Afterrefluxing two hours, azeotropic distillate was collected which separatedinto about 700 cc. of an olefinic layer and 280 cc. of dioxane.Additional dloxane (250 cc.) was added to the reaction mixture. Thecontents of the fiask were than poured into two liters of water, and theoily product was allowed to crystallize'overnight. The solid wascollected on a filter, washed with pentane to remove color,recrystallized from aqueous 90:10 ethanol-methanol, and washed withpentane. Three crops were obtained. The pentane washings containing thebrown impurities were reduced in volume on the steam bath and wereallowed to stand for several days. The resulting crystalline mass waswashed with pentane, filtered, and dried. The total yield I of2,8-dimethyl-2,8-dipropylazelaic acid was 450 grams,

representing 60 percent of the theoretical amount based on1,5-dibr-omopentane. Melting range on each crop was 95110 C. Infraredspectra showed that the crops were essentially identical with oneanother. Acid No.1 calculated, 374; found, 375.

Example X V.Preparati0rz of di-(2,2-dim ethylhexyl)2,8-dimethyl-2,8-dipr0pylazelate This product was prepared from2,2-dimethylhexanol and the acid prepared in Example XIV by a proceduresimilar to that used in Example IX.

Example XVI.P1-eparati0n of 2,8-dimethyl- 2,8-diethylazelaic acid Thismaterial was prepared by a procedure similar to that used in ExamplesVII and XIV.

Example X VII .Preparation of di-(2,2-dimethylhexyl)2,8-dimethyl-2,8-diethyluzelate This product was prepared from2,2-dimethylhexanol and the acid prepared in Example XVI by a proceduresimilar to that used in Example IX.

Example XVIIl.-Preparation of di-(IHJHJH-Dodizcafluoro-I-heptyl)2,2,8,8-tetraethylazela'te Materials Mole Moles Quantity Weight2,2,7,8-tetraethylazelayl chloride 337 337 g.

1 (theory).- Pyridine 79. 1 1. 45 115 g. 07 Fluoroalcohol 332 1. 43477.5 g. Benzene, ACS r g nt 350 cc.

1 Estimated.

material formed in the flask during this time. Sufficient 22 water wasadded to dissolve the solids present, and sufiicient pentane was addedto cause the organic layer to float. The organic layer was washed withdilute hydrochloric acid, water, and 10 percent sodium hydroxide. Alarge amount of a heavy red liquid settled to the bottom of theseparatory funnel with each sodium hydroxide washing. This lower layer,weighing 261 grams, was found to be the fluoroalcohol. When no morefluoroalcohol separated during the sodium hydroxide washing, the

organic layer was washed with water until neutral, and dried. Anattempt'was made to distill the solvents and other volatile materialsfrom the crude ester, but copious acidic fumes were evolved. The crudeester was then filtered through alumina, but acid fumes were evolvedagain when the product was heated to 195 C. under 0.75 mm. pressure. Theinfrared spectrum indicated presence of considerable anhydride.

After treating three times with dilute methanolic potassium hydroxide,the infra-red spectrum showed no anhydride. The acid number was 0.67,but it had not proved susceptible of reduction by the base treatment.Gasliquid partition chromatography furnished an assay of 95.8 percent.

Example XIX.-Preparation of di-(2,2-dfmet/1yloctyl)3,3-dimethylglutarate This product was prepared from commerciallyavailable 2,2-dimethyloctanol and 3,3-dimethylglut-aric acid by aprocedure similar to that used in Example IX.

Example XX.--Preparation of di-(2,2-dii11etlzyllzexyl)3,3,6,6-telramethyIsuberate This product was prepared by the followinggeneral Example XXI.Prepa1-ati0n of Z-methyl-Z-ethyl- 1,3-pr0panedi0ldi-(2,2-diethylpentan0ate) A. Preparation of 2,2-diethylpentanoic acid:

2,2-diethylpentanol was convertedto 2,2-diethylpentanoic acid accordingto the procedure of J. Kenyon and B. C. Platt (J. Chem. Soc. 633, 1939).Yields of 53 and 48 percent were obtained. A typical preparation was asfollows.

Materials Mole Moles Quantity Weight 2,2-diethylpentanol-1 144 l 144NaOH analytical reagent. 40 0. 75 30 KMnO, analytical reagent- 158 2. 15340 S0 commercial Procedure.'-Potassium permanganate (340 grams) in 3000cc. of water was added slowly to a well-stirred mixture of 144 grams2,2-diethy1pentanol and 30 grams sodium hydroxide dissolved in 250 cc.of water. After twelve hours, the heat of reaction had dissipated. Themixture was then heated to C. for one hour. Gaseous sulfur dioxide wasintroduced into the solution until it was acidified and the manganesedioxide went into solution. The organic layer formed was taken up inether, washed well with water, and dried over Drierite. The filteredsolution yielded 84 grams of 2,2-diethylpentanoic acid, distilling atl33-137 C. at 17 mm. Hg. pressure. The yield was 53 percent, based onalcohol. Acid number: calculated, 35 4; observed, .348.

Materials Mole Moles Quantity,

Weight Diethylpentanoyl chloride 176 0.98 172 g.2-methyl-2-ethyl-1,3-propane 118 .425 50 g. Pyridine, pruified 200 cc;

Procedure.-2,2-diethylpentanoyl chloride (172 grams) was slowly added toa mixture of 200 cc. of pyridine and 50 grams of2-methyl-2-ethyl-1,3-propanediol. The reaction mixture was externallyheated during the addition, and solid began forming at 88 C. It was thenheated to 100 C. for three hours. Methanol (20 cc.) was added, and themixture was stirred for one hour. Water was added, and the product wastaken up in ether, washed with dilute hydrochloric acid, washed withwater until neutral, dried over Drierite, and distilled. The Z-methyl- 2ethyl 1 1,3-propanediol di (2,2 diethylpentanoate), weighing 140.5grams, distilled at 140-147" C. at 0.05 mm. The yield was'83 percent,based on alcohol. Gasliquid partition chromatography indicated that theester was 90.1 percent homogeneous.

Example XXII .Preparation of Z-mctlzyI-Z-ethyl-I,3-prpanedioldi-(Z-ethyl-2-is0pr0pylhexan0ate) This product was prepared by thefollowing general procedure:

(1) 2-ethylhexanoyl chloride was prepared from 2- ethylhexanoic acid,

(2) Triethylcarbinyl 2-ethyll1exanoate was prepared from 2-ethylhexanoy1chloride and triethylcarbinol,

(3) Triethylcarbinyl 2-ethyl-2-isopropylhexanoate was prepared fromtriethylcarbinyl Z-ethyl-hexanoate and isopropyl bromide,

(4) Triethylcarbinyl 2-ethyl-Z-isopropylhexanoate was hydrolyzed to form2-ethyl-2-isopropyl hexanoic acid,

(5) 2-ethyl-2-isopropyl hexanoic acid was converted to the chloride,

(6) '2-methyl-2-ethy1 1,3 propanediol was acylated with2-ethyl-2-isopropylhexanoyl chloride to form the product.

In the examples the expression GLPC refers to gas liquid partitionchromatography. This analytical technique is adequately described ineither of the following publications:

Analyst, 77, 1952, pages 915-932, or Petroleum Refiner, November 1955,pages 165-169.

In addition to the data shown, infrared spectra were determined on thevarious esters.

TESTING PROCEDURES (EXAMPLES VII-XXVII) Thermal stability in glass(copper present).-A 20- gram sample of the ester is placed in a tube cm.long and 2.5 cm. in diameter and fitted with a side arm 8 cm. from thetop of the tube to which is attached through a standard taper joint aU-tube containing mercury. At the top of the test tube is a 24/40standard taper joint to which is fitted a stopcock with an 8 mm. ID.tube extending inside the test tube to within 10 cm. of the bottom. Thestopcock is opened, and the testing tube is flushed with nitrogen,leaving a slight positive pressure. The tube is immersed in an aluminumblock bath and heated to 600 F. for 48 hours. The weight loss due tovolatility, the percent viscosity change, and the acid number increaseare noted. Percentage decomposition is calculated from the acid numberincrease, using the theoretical saponification number as representativeof 100 percent decomposition. The test was conducted in the presence ofa 1 by 6 cm. copper strip. The weight change of the copper isdetermined.

Thermal stability in steel.A 20-ml. sample of the ester is placed in acylinder 7 inches long made from threequarter-inch stainless steeltubing. A gauge is attached for pressure reading. The bomb is sealedunder one atmosphere of nitrogen and immersed in an aluminum block bathfor 6 hours at 600 F. (316 C.). The gauge pressure during the test andafter cooling, the percentage viscosity change, and the acid numberincrease are obtained. Percentage decomposition is calculated from theacid number increase using the theoretical saponification number asrepresentative of 100 percent decomposition.

Hydrolytic stability.Hydrolytic stability was determined by means ofsaponification number. The saponification number obtained on the samplewas compared to the theoretical saponification number.

The procedure used a 2 hour reflux of the ester sample in alcoholic KOH.ASTM procedure D-94 was employed.

Physical tests.-The various physical tests employed ASTM procedures.

TABLE V.PHYSIOAL PROPERTIES OF ESTERS IN EXAMPLES VII-XXII PourKinematic Viscosity (05.) Flash Ester Point, ASTM Point,

F. Slope 13 -40 F. 100 F. 210 F.

Di-(2methyl-2ethylpentyl) 2,2,8,8-tetraethylazelate- -20 144. 3 9. 500.847 465 Di-(2,2-dimethylhexyl) 2,2,8,8-tetraethylazelate -25 106. 1 8.47 0.830 450 Di-(2,2-dimethy1octyl) 2,2,8,8-tetraethylazelate -40 93. 919.82 0. 776 460 Di-(2,2 dimethyldecyl) 2,2,8,8-tetraethylazelate -45112. 7 10. 51 0. 742 495 Di-(2,2-di1nethy1hexyl)2,2,6,6-tetrarnethylpimelate -60 44, 822 20. 56 3. 71 0. 813 380Di-(1H,1H,7H-d0decafiuoro-Lheptyl) 2,2,8,8-tetraethylazelate. -20 105.47 7. 27 0. 900 Di-(2,2-dimethyloetyl) 3,3-dirnethy1gultarate 13, 28220.83 3. 93 0.775 Di-(2,2-dimethylhexyl) 3,3,6,6-tetramethylsuberate -6530, 000 41. 13 5. 55 0. 790

' Di-(2,2-dimethy1hexyl) 2,8-dimetl1yl-2,8-diethylazelate -25 52. 48 5.87 0. 842 Di-(2,2-di1nethylhexyl) 2,8-dimethyl-2,8-dipropylazelate -4069. 64 (i. 67 0.842 2-methyl-2-ethyl-l,3-pr0panedioldi-(2,Z-diethylpentanoate) -40 32. 98 4. 43 8522-methyl-2-ethyl-1,3-propauediol di-(Zethyl-2-isopropylhexanoate) -40109. 4 7. 97 862 1 Data not obtained.

TABLE IX.DATA ON THERMAL STABILITY IN STEEL PRESSURE CYLINDER ESTE RS OFEXAMPLES VII-XXII Viscosity at 100 F. (as) Acid Percent Ester NumberDecompo- Original Final Percent Increase sition 2 ChangeDi-(2,2-dimethy1hexyl) 2,2.8,8-tetraethylazelate 106. 1 99. S4 5. 9 3.4 1. 6 Di-(2,2-dimetl1ylhexyl) 3,3,6,0-tetramethyl suberate 41. 13 40.85 0. 7 1. 3 0. 5 Di-(2,2-dimethyloctyl) 3,3-dimethylglutarate 20. 8319. 51 6. 3 2. 1 O. 8 Di-(1H,1H,7H-dodeeafiuoro-1-heptyl) 22,8,8-tetraethylazelate 105. 45 93. 27 -11. 6 2. 8 2. 4 Di-(isooetyl)azelate- 12. 58 10. 94 13. 32. 4 11. 9 Di-(Z-ethylhexyl) sebacate 12. 5911.63 7. 6 30. 2 11.5 Di-(2,2-diethylpentyl) azelate.. 25.32 11. 96 52.8 58. 1 22. 8 2-1nethyI-Z-ethyl-l,3-propanedio1 d1 (2,2-diethylpentanoate) 32. 98 31. 91 3. 2 5. 4 1. 9

1 A 20-ml. sample is maintained at 600 F. (316 C.) for six hours undernitrogen. 2 Percentage decomposition=100 (acid numberincrease)/(theoretical sapouihcationjnumber).

TABLE X.PHYSICAL PROPERTIES-TESTERS OF EXAMPLES XXIII-XXVII Viscosity inCentistokes ASTM Pour Flash Slope Point, Point, F. F. 40 F. 100 F. 210F.

2,2-dimethylvalerates:

2-ethyl-2-butyl-1,3-pr0panediol 10, 610 13. 41 2. 87 32 3302,2,5,5-tetramethyl-1,G-hexanediol 20, 280 17. 72 3. 48 0. 30 -70 342-methyl-2-ethylhexanoates:

2-methyl-2-propyl-1,3-propanetli0l 23. 88 3. 67 0, 7 3752,2,5,Metramethyl-l,Eehexanediol 46. 5. 22 0, 3 3802,2-dimethyltetradecylatez 2methyl-2- propyl-1,3-propanedi0l 1 10,61636. 82 6. 35 0 9 435 1 Viscosity at F.

TAlKLE XI.THERMAL AND IIYDROLYTIC STABILITY 3 DATA-ESTERS OI" EXAMPLESXXIII-XXVII Example XXIII .Prepamtion of 2-ethyl-2-butyl-1,3-propanediol ester of 2,2-dimethylvaleric acid The preparation of theacid employedv a procedure similar to that used in Example VII, with theexception that a monobromide, instead of a dibromide, was used.

The glycol used was commercially available. The esterification procedurewas similar to that used in Example IX.

Example XXlV.-Preparation of 2,2,5,5 tetramethyl-L6- hexanediol ester of2,2-dimethylvaleric acid The preparation of the acid employed aprocedure similar to that used in Example VII, with theexception that amonobrom'ide, instead of a dibromide, was used.

The 2,2,5,5-tetramethyl-1,6-hexanediol was prepared as follows:

In a 3-liter, 3-necked flask fitted with a Trubore stirrer, droppingfunnel, and reflux condenser with drying tube, 36 grams (0.95 mole,metal hydrides) of lithium aluminum hydride were slurried in 600'"ml.ofdry tetrahydrofuran. While the slurry was rapidly stirred, 126.2

grams (0.625 mole) a,a,a,tx'-tetramethyladipic acid dis- 0 solved in1,150 ml. of dry tetrahydrofuran were added from the dropping funnel ata rate which maintained gentle reflux (90 minutes).

The reaction was refluxed for 30 minutes, and then 1 liter oftetrahydrofuran was distilled from the flask with stirring. The flaskwas cooled with an ice bath; then 300 ml. of H 0 were added, verycarefully at first, followed by 150 ml. of concentrated sulfuric acid in1 liter of water and finally by 600 ml. of ether.

In a separatory funnel, the water phase was drawn off and discarded. Theether phase was extracted with 250 ml. of 10 percent sodium bicarbonate.Acidification of the bicanbonate extract gave 31.5 grams of unreactedacid. This was immediately reduced by the procedure just described.

The ether solutions from both reductions were combined, dried withsodium sulfate and calcium chloride, and stripped of ether. The product,a tan solid, was distilled in a Koelsch flask at 0.5 mm. The yield ofwhite, waxy material, M.P. 76-79 C., was 76.8 grams (0.441 mole, 71percent).

No carbon-hydrogen analysis was made of this new diol itself, but thecomposition of its pivalate ester was determined and found to check withthe theoretical value.

The ethyl ester of a,a,a,a-tetrarnethyladipic acid was also made andreduced to the diol. A solution of grams (0.173 mole) of the crude acid,300 ml. of absolute ethanol,- and 5 ml. of concentrated sulfuric acidwas refluxed for 14 hours and poured into a separatory funnel with etherand water. After extraction with 10 percent Na-HCO and drying, the ethersolution was stripped of ether. Distillation through a short Vigreuxcolumn gave 28.5 grams (0.111 mole, 64 percent) of colorless liquid,B.P. 92*94" at 2 mm.

Using a 1-liter, 3-necked flask equipped with Trubore stirrer, refluxcondenser, and dropping funnel, 28.5 grams (0.111 mole) of the esterwere added at reflux rate to a slurry of 4.5 grams (0.119 mole, metalhy- The mixture was refluxed for 30 minutes after theaddi- 7 tion. About40 ml. of H 0 were added carefully to The preparation of the acidemployed a procedure similar to that used in Example VII, with theexception that a monobromide, instead of a dibromide, was used.

The glycol used was commercially available.

The esterification procedure was similar to that used in Example 1X.

Example XX VI .-Preparation of 2,2,5,5-tetramethyl-1,6- hexanediol esterof Z-methyl-Z-ethylhexanoic acid The preparation of the acid employed aprocedure similar to that used in Example VII, with the exception that amonobromide, instead of a dibrornide, was used.

The preparation of the glycol is described in Example XXIV.

The esterification procedure was similar to that used in Example IX.

Example XXVIL-Preparation of 2-methyl-2-pr0pyl-1,3- propanediol ester of2,2-dimethyltetradecanoic acid The preparation of the acid employed aprocedure similar to that used in Example VII, with the exception that amonobromide, instead of a dibromide, was used.

The glycol used was commercially available.

The esterification procedure was similar to that used in Example IX.

While particular embodiments of the invention have been described, itwill be understood, of course, that the invention is notlimited-thereto, since many modifications may be made; and it is,therefore, contemplated to cover by the appended claims any suchmodifications as fall within the true spirit and scope of the invention.The invention having thus been described, what is claimed and desired tobe secured by Letters Patent is:

1. Chemical compounds having the formula where R R and R are acyclicalkyl groups of from 30 1 to 18 carbon atoms and where A, is selectedfrom the group consisting of:

where R; is an acyclic alkyl group of from 1 to'4 carbon atoms and n isan integer of from 1 to 10.

2. The chemical compound Z-methyl-Z-ethyl-l,3-propanedioldi-(2,2-diethylpentanoate).

3. The chemical compound 2-methyl-2-ethyl-l,3-propanedioldi-(2-ethyl-2-isopropylhexanoate) References Cited by the ExaminerUNITED STATES PATENTS 2,847,383 8/1958 Airs et al. .4 260-485 2,850,5289/1958 Closson 260-537 2,852,470 9/1958 Henne et al. 260-485 2,857,42110/1958 Matuszak et al. 260-485 2,889,354 6/1959 Blake et al 2 60-4852,921,957 1/1960 ORear et al 260-485 3,049,557 8/1962 Emrick 260-41063,081,342 3/1963 Ver Nooy 260-485 OTHER REFERENCES Adams et al.:J.A.C.S., vol. 73, pp. 13 614l (1951). Asano et al.: Chemical Abstracts,vol. 45, p. 5617c Barnes et al.: Lubrication Engineering, pp. 454-458(1957).

Birch et al.: Chemical Abstracts, vol. 47, p. 1031d (1953).

Cason et al.: Journal of Org. Chem., vol. 14, pp. 1036 1038 1949).

Hauser et al.: Journal of Org. Chem. Soc., vol. 78, pp. 3837-3841(1956).

Wagner and Zook: Synthetic Organic Chemistry, John Wiley and Sons, Inc.,New York (1953), pp. 484 and 488-491.

References Cited by the Applicant Encyclopedia of Chemical Technology,R. E. Kirk and D. F. Othmer, vol. 9, pp. 699-712, InterscienceEncyclopedia, Inc., New York, 1952.

LORRAINE A. WEINBERGER, Primary Examiner.

LEON ZITVER, Examiner.

I. R. PELLMAN, Assistant Examiner.

1. CHEMICAL COMPOUNDS HAVING THE FORMULA